The point is to have fun and when you are at the stage of squeezing juice from a rock, to make a new character with a different build and have fun with that. And then to get new systems or builds and have fun with them. And perhaps eventually to find some other game that is more fun and play that for a while. And then to come back and see what’s new and enjoy it.
Games are for fun. There’s fun in having them reward you for better/more dedicated play, but the play and the experiences are where the fun is. If you want a memento, take a picture of your end-of-season character. If earning trophies and permanent records of your prowess is your goal, you need to play a game with an organized sporting league (and be good at it).